* curves, each curve being a sequence of four
            2D tuples.
        max_errors: A sequence of *n* floats representing the maximum permissible
            deviation from each of the cubic Bezier curves.

    Example::

        >>> curves_to_quadratic( [
        ...   [ (50,50), (100,100), (150,100), (200,50) ],
        ...   [ (75,50), (120,100), (150,75),  (200,60) ]
        ... ], [1,1] )
        [[(50.0, 50.0), (75.0, 75.0), (125.0, 91.66666666666666), (175.0, 75.0), (200.0, 50.0)], [(75.0, 50.0), (97.5, 75.0), (135.41666666666666, 82.08333333333333), (175.0, 67.5), (200.0, 60.0)]]

    The returned splines have "implied oncurve points" suitable for use in
    TrueType ``glif`` outlines - i.e. in the first spline returned above,
    the first quadratic segment runs from (50,50) to
    ( (75 + 125)/2 , (120 + 91.666..)/2 ) = (100, 83.333...).

    Returns:
        A list of splines, each spline being a list of 2D tuples.

    Raises:
        fontTools.cu2qu.Errors.ApproxNotFoundError: if no suitable approximation
        can be found for all curves with the given parameters.
    c